Field of the Invention (Technical Field)
The present invention relates to a valve position indicator and a method for indicating a valve position.
Description of Related Art
Valve position indicators are known in the art. Such indicators are based on a linear movement of an indicator, wherein a movement of the valve stem or spindle is linearly translated into a movement of the valve position indicator (a so-called “rising stem indicator”). As a consequence, a predetermined position of the indicator is obtained by means of a linear movement, resulting in an inaccurate reading of the indicator.
Furthermore, ODO-meter type rotation counters are known that indicate the number of rotations of a valve stem or spindle. Setting such indicator to exactly identify a fully opened or closed position is a complicated operation.
The disadvantage of linearly moving indicators, that lead to a very uncertain positioning of the indicator and as a consequence is not fit for use in an automated system, has been obviated by valve position indicators that apply an axle that is operably connected with said valve and wherein a repositioning of said valve induces a rotation of said main axle, said main axle being partly provided with a toothless portion, such that rotation of said main axle only intermittently induces a rotation of an indicator. A linear rotation of said valve therefore more or less yields an on/off behavior of said indicator. Examples of these indicators are mentioned in EP 0702178, U.S. Pat. No. 3,505,972 and U.S. Pat. No. 4,893,582.
However, these valve position indicators still suffer from disadvantages.
Therefore, an improved valve position indicator is highly desirable.